BANGKOK, Thailand (AP) - When HIV first escalated in Africa and the Caribbean, Asia remained virtually untouched and unaware. But the world's most populous continent is catching up.

Today, 25 years into an epidemic that has claimed 25 million lives worldwide, the Asia-Pacific region has the highest number of infections after sub-Saharan Africa.

The big question now is: How far will it go?

"I don't think it will go the African way," where in some areas up to a third of the population is infected, UNAIDS chief Dr. Peter Piot said in an interview with The Associated Press. But "there's slow but steady growth and with that kind of population denominator, the numbers are staggering,"

UNAIDS, the U.N. body leading the global war on AIDS, estimated 8.3 million people were living with the virus last year in the Asia-Pacific — and nearly 85 percent of those infected had no access to antiretroviral treatment.

The disease, first identified in the United States in an announcement by health officials on June 5, 1981, quickly went global. In Asia, a vast, diverse and mobile population has helped spread the virus, starting with unprotected sex and dirty needles. It first devastated Thailand's infamous sex industry, later reached millions in India and has pushed once-isolated communist Vietnam to the brink of an HIV explosion.

India is home to more HIV/AIDS-infected people than any other country, according to new UNAIDS numbers. Its estimated 5.7 million infections last year comprise more than two-thirds of all cases in the Asia-Pacific region.

In a country of more than 1 billion people, that number shrinks to a small fraction — 0.9 percent of adults compared to South Africa's almost 19 percent. But a small percentage can cause the problem to be neglected.

"Because of this low percentage, the issue doesn't seem to be a priority for political leaders and also for the man on the street," said Dr. Shigeru Omi, the Western Pacific regional director for the U.N.'s World Health Organization.

India's epidemic is largely driven by heterosexual sex — mainly prostitutes and their clients who do not use condoms. In the country's south, a recent report found, prevention campaigns targeting sex workers have resulted in a 35 percent drop in new cases among 15 to 24 year olds.

But there has been little progress in India's highly populated north or drug-ridden northeast, said Prabhat Jha, of the University of Toronto, one of the study's authors.

"It's too early and one wouldn't want to be the fellow on the Titanic who said, 'All clear,' because the north is 70 percent of the population," said Jha, who's spent a decade researching AIDS in India. "If it explodes, you can imagine what would happen."

Chandi Sayeed, 39, of Bombay's gritty brothel district, said she was sold into prostitution at age 16 when she was already a mother of two.

"The problem is most women don't use condoms with their husbands or with customers they love," she said. "They only use it with men who aren't regulars. They say, how can we use it with our lovers? But women must think of their children and their family first."

Another trouble spot is Papua New Guinea, which shares an island north of Australia with Indonesia's easternmost Papua province.

The country of 5.7 million is plagued by political instability, poverty and rampant sexual violence against women. It has the Asia-Pacific's highest adult per capita infection rate of 1.8 percent, but the political will to tackle the problem is absent.

"Papua New Guinea is a very, very, very serious situation," Omi said. It "needs some special attention, otherwise there's a possibility that Papua New Guinea will become like Africa in the future."

In China, the AIDS picture is still a bit unclear. But its sheer size — some 1.3 billion people — is enough to worry experts.

In January, China and the United Nations lowered HIV/AIDS estimates there, saying roughly 650,000 people were infected in 2005 — nearly 200,000 fewer than an earlier projection.

Injecting drug users accounted for nearly half the infections in China, where the government was accused of being slow to address the problem. HIV took off in China in the early 1990s when farmers began selling blood plasma to earn extra money.

AIDS activists and people infected with the virus have been harassed, but top leaders have finally admitted publicly that a problem exists.

In late 2004, President Hu Jintao was photographed shaking hands with HIV-infected Zhang Hulin. It was a major step for the communist government, but Zhang says he and his family suffered even greater stigma and discrimination after the photos circulated.

Still, he remains hopeful a cure will be found.

"It's one of these diseases that the whole world is concerned with and doing research on," said Zhang, who tested HIV-positive in 1997. "So maybe it can be eradicated, but it's hard to say."

In Vietnam, the bulk of infections are among prostitutes and injecting drug users. But the virus has spread to all provinces and cities, and the country is at a very critical moment, Omi said.

With prevention campaigns, "they may be able to avert transmission into the community. But if they fail, they may end up having widespread transmission among the general public," he said.

Vietnam is the only Asian nation among 15 countries selected to receive emergency HIV/AIDS funding under a $15 billion Washington plan.

Thailand and Cambodia, in contrast, have been hailed as two bright spots in Asia. Both still have adult per capita infection rates over 1.4 percent, but the governments have largely reversed once-devastating epidemics by promoting 100 percent condom use among prostitutes working in brothels.

But both countries must refocus and refresh their prevention campaigns, said Jeanine Bardon, regional director of U.S.-based Family Health International.

Trends have shifted and HIV has latched on to new risk groups, including men who have sex with men; young people with multiple sex partners; injecting drug users; and monogamous women whose husbands have sex outside marriage.

"It's not just sex workers and their clients. It's much more complicated now," she said. "The new infections are now occurring between the men who got infected (by prostitutes) in the '90s and their wives."

Children are among the most tragic AIDS victims. There were an estimated 1.5 million children orphaned by AIDS in the Asia-Pacific, with more than 120,000 of them infected in 2004, UNAIDS estimated.

Often, they are unwanted, said Joseph Maier, a Catholic priest who runs Mercy Center orphanage, school and hospice in a Bangkok slum.

"Nobody's talking about, 'Come on, why don't we adopt some of these kids?" Nobody's talking about, 'Hey, these kids are bright, they're geniuses, there's poets among them,'" said Maier, known to everyone as Father Joe.

Thailand has made cheap antiretroviral drugs easily available, which has increased life spans but not reduced the stigma and discrimination.

"We walk around to all the schools in this area here and say we've got some kids with HIV/AIDS, we want you to take them in," Maier said. "They wouldn't let them in."

If more isn't done to combat HIV/AIDS now, Asia could surpass Africa — where 25.8 million are now infected — in the number of people living with the virus, said Bardon. The tragedy would be all the greater because today people know how to prevent it.

"We'll have lost an enormous opportunity to avert thousands of infections and eventually millions of lives saved," she said. "It's not that we don't know what we're doing."